."> IS i'UNVll'l.Ks oF rilKMlSTUY 



many metals. Tl xidation of those metals which are able to form 



acid oxides \\ith an excess of oxygen is especially remarkable. In 

 this ca-e they remain in combination with potassium oxide as potassium 

 salts. Manila ne.se, antimony, arsenic, iron, chromium, A.V., are in- 

 -t a i ices i if tin- kind. These elements, like ca rb< >n aid sulphur, displace 

 free nitrogen. The lower oxides of these metals \\ht-n fused with nitre 

 pa-s into the higher oxides. ( ir^anic substances are also oxidised 

 when heated with nitre that is, they burn at the expense of the nitre. 

 It will be n-adilv understood from this that nitre is frequently used in 

 chemical practice and t he arts as an oxidising auent at hi^h temper- 

 atures. Its application in //"///">/''/,/ is based mi this : gunpowder con- 

 sists of a mechanical mixture of tinely-^round sulphur, nitre, and char- 

 coal. The relative proportion of these substances varies according to 

 the destination of the powder and to the kind of charcoal employed (a 

 friable, incompletely-burnt charcoal, containing therefore hydrogen and 

 oxygen, is employed). (Jases are formed in its combustion, chielly 

 nitron-,.)) and carbonic anhydride, which create a considerable pres- 

 sure if their escape be in any way impeded. This action of gun- 

 pouder may be expressed by the equation : '_' K N <>., + :>(' -f S= K ,,S 4- 



It i- found by this equation that gunpowder should contain thirty- 

 six parts of charcoal ( I ">;> p.c. ). and thirt v-two parts ( 1 1 - ( .l p.c. ) of sul- 

 jihnr. to L'M-J part s ( 7 1 '> ]).c. ) of nitre, which is verv near to its actual 

 ci imposition. '" 



''' In rhaia. win re the nianiifactiire of L. f uiipowder lias loiip; heeii practised, they use 



7.V7 ol ' : . 1 r J of charcoal, and ( .l'!l of sulphur. < Irdimiry p, >w der for sporting purposes 



-" ; ,,] nitre. ]-2 of charcoal, and .s ,,( -ulphur. \\hil-t the gunpowder used 



v,ln-ii i.eated to i'.un , uheti struck, or l,\ contact with a spark. A compactor finely- 



1 1 1 ';.'! \ . I'o act properly t he irunpou'der must ha\ i' a known 

 , -. n. ~o that the prer-~nre -Imulil increase and not diminish during the 



j . .-. d.-r tin ape < .t c, -ided pri ins u it h holes through them (prismatic 



: 



I mi the r.-a on of the dynamical .icti-.n i.f ;j unp< <\\ .1. -r. a nd i -J i a solid residue, 



iv-idiie I.IK . ' nta M p.. i mm -ulphide. K S. and a wliol.- series ,,f 

 . , arlionate and nlphate. Thi- alread\ -hows that tin- comluis- 

 iiot o imple .1 it appeal to he from the aho\e fiii'iiiula. and hence 

 , , due i- al-t greater than mdieated l.ythat formula. According to 

 27ii part- ol /iiiii nwdi > 1 1 n pa 1 1 - of r sidue that is, I dii part - of 



,, 7n p. ,-, 'enerally .V. p.c.i. 'I'd ditTerence depends on the fact that .so 

 ol the nitivi remain- in the n id ue. and it i- evident that if the residue 

 i p, i ion of t lie /.' < , , ol\ed li\ I lie powder will \ary also, ami therefore 



